code: def reset_gru(gru):
      # in order to run fprop multiple times
      # for the gradient check tests the
      # gru internal variables need to be
      # cleared
      gru.x = None
      gru.xs = None  # just in case
      gru.outputs = None
      return
  
file_path: neon/tests/test_gru.py
imports: import itertools
  import numpy
  from neon import NervanaObject, logger
  from neon.initializers.initializer import Constant, Gaussian
  from neon.layers import GRU
  from neon.transforms import Logistic, Tanh
  from neon.layers.container import DeltasTree
  from gru_ref import GRU
  from utils import allclose_with_out
label_desc: Use image node_id 6 for calling a global function with example usage: reset_gru(gru) without return types